The present invention relates to processing substrates in a vacuum chamber. More particularly, the field of the invention is sputter coating of semiconductor wafers, and apparatus for effecting such metallization coating of wafers individually, and on a serial, continuous basis. The invention is an improvement in the arrangement for pumping the load lock of the vacuum chamber, which increases the rate of processing and decreases the costs.
In such continuous throughput systems, wafers must be introduced into the vacuum chamber through a load lock in order to prevent exposing the vacuum condition in the chamber to the air outside the chamber.
When a wafer is to be loaded into the chamber, the inner closure means, such as a sealing plate, is activated to seal the inner side of the opening, and then the outer closure means, such as a sealing door, is opened. Next the door is opened, a wafer is inserted through the opening, and the door is again closed. The load lock chamber now containing the wafer is pumped down to contain an atmosphere compatible with the atmosphere in the processing vacuum chamber, and then the inner sealing plate is moved away from the opening to expose the wafer for processing in the main vacuum chamber.